In related art, a brightness value of the backlight source of a pattern generator cannot be displayed autonomously. To monitor the brightness value of the backlight source of the pattern generator, an operator has to hold and align a brightness testing instrument with the backlight source to monitor the brightness value. Such monitoring method is complicated and cumbersome. The monitoring result may be inaccurate due to great impact of human factors.
In the related art, during a period for monitoring the brightness value of the backlight source of the pattern generator, if it tends to adjust the brightness value of the backlight source, since an adjustable switch for the backlight source is arranged within the pattern generator, as shown in FIG. 1, a substrate 2 covering the backlight source 1 has to be removed from the backlight source 1, and then, as shown in FIG. 2, a sliding rheostat RR may be adjusted, so as to adjust the brightness value of the backlight source of the pattern generator. In this way, the substrate 2 is liable to be dislocated and requires a re-alignment adjustment, thereby increasing a downtime and decreasing a utilization rate of the pattern generator.